Electrode contact device

ABSTRACT

An electrode contact device for use with metallurgical electric furnaces which comprises a copper body member and a contact member in the form of a powder metallurgical compact consisting essentially of copper and tungsten.

United States Patent Smith [4 1 June 20, 1972 [s41 ELECTRODE CONTACT DEVICE [56] References Cited 72] lnventor: Arthur E. Smith, Niagara Falls, NY. UNITED STATES PATENTS [73] Assignee: Union Carbide Corporation, New York. 1,702,359 2/1929 Molmark ..l3/l6 UX N.Y. 2,915,573 l2/l959 Foyn et al ..l3/l6 [22] Flled: May 1971 Primary Examiner-Bemard A. Gilheany [21 Appl. No.: 143,955 Assistant Examiner-R. N. Envall, Jr.

Attorney-Paul A. Rose, Harrie M. Humphreys, Robert C.

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[52] us. Cl ..13/14, 13/16, 339/263 E, Cummmgs em J Mc a y r [51] Int. Cl. ..H05b 7/10 1 [58] Field of Search 1 3/14, 15 16, 17; 339/1 [4, An electrode contact device for use with metallurgical electric furnaces which comprises a copper body member and a contact member in the form of a powder metallurgical compact consisting essentially of copper and tungsten.

2 Claims, 3 Drawing Figures PA'TE'NTEDmzo I972 FIG.

I INVENTOR ARTHUR 5. sum! BY vfm/flw ATTORNEY ELECTRODE CONTACT DEVICE BACKGROUND OF THE INVENTION This invention relates to an electrode contact device. More particularly, this invention relates to an electrode contact device for use in electric metallurgical furnaces.

At the present time many metallurgical processes involve the use of electric furnaces in which high electrical currents are applied to carbon or graphite electrodes for heating purposes. The application of electrical current is most often applied through contact plates rnade of copper which are often times water-cooled in an effort to protect the contact plates from the high temperatures encountered in operation. However, due to the very high temperatures involved and the expo sure of the contact plates to hot corrosive gases emanating from the furnace, the contact plates are eroded and wear out after relatively short periods of time thus causing an economic detriment due to replacement costs and furnace .down-time.

It is therefore an object of the present invention to provide an improved electrode contact having increased life and effectiveness,

Other objects will be apparent from the following description and claims taken in conjunction with the drawing in which FIG. 1 shows an electric furnace utilizing an improved electrode contact in accordance with the present invention and FIGS. 2 and 3 more fully illustrate the electrode contact of the present invention I Broadly, an electrode contact device in accordance with the present invention comprises a copper body member and a contact member integrally bonded thereto, the contact member being in the form of a powder metallurgical compact consisting essentially of copper and tungsten.

With reference to the drawing, FIG. I shows an electric furnace 1 containing a solid charge 3 and molten metal 5. The furnace l and the charge 3 therein are heated by electrode 7 which receives electrical current via power lead 9 from a power source (not shown). Power lead 9 is connected to a copper electrode body member 11 to which is integrally bonded a copper-tungsten contact member 13. As shown in FIG. 1, copper-tungsten contact member 13 shields copper body member 11 from electrode 7 and also from hot corrosive gases which emanate from the furnace charge 3 in the vicinity of region 15. Copper-tungsten contact member 13 is highly resistant to elevated temperatures and hot furnace gases and thus results in a longer life for the electrode contact comprising body member 11 and contact member 13.

The electrode contact device of the present invention can be manufactured by conventional powder metallurgy techniques. For example, tungsten powder having an average size of 5-6 microns is tamped in a die to a density of about 8.8 grams/cc. Subsequently the shape is sintered at a temperature of about 2,200 F. to provide a sponge-like coherent article. The tungsten shape is then surrounded by elemental copper and heated at about 2,200 F. in an Nl-l atmosphere for a time sufi'rcient for the copper to melt and substantially fill the intertices in the tungsten shape. Excess copper is removed from the surface and the article is etched with molten Na N0 for about 8 minutes and thereafter washed with water. The portion of the surface of the article to be in contact with the copper body member is tinned with high purity copper or brass (85%Cu, 15%Zr). The contact member prepared as above is placed in a mold and, following conventional practice, molten copper is poured into the mold and upon solidification of the copper, a device as illustrated in FIG. 3 is obtained. In such a device, tungsten'copper contact member 13 is integrally bonded to copper bodymember 11. Body member 11 can be provided with a cooling passage 15 and cooling conduits 17 and 19.

As regards the composition of tungsten-copper contact member 13, suitable ranges are 40 to 32 percent by weight copper and to 68 percent by weight tungsten. It has been found that with the aforementioned compositional range, a

coherent contact member can be obtained which will strongly and rntegrally bond with a copper body member to provrde an excellent electrical connection therewith.

What is claimed:

1. An electrode contact device for use in a metallurgical electric furnace having an electrode for the heating thereof comprising a copper body member and a contact member integrally bonded thereto, said contact member being in the form of a powder metallurgical compact and consisting essentially of copper and tungsten, said contact member substantially covering the portions of the copper body-member adjacent to the electrode of the electric-fumace 2. An electrode contact in accordance with claim 1 wherein the contact member consists essentially of from about 32 to 40 percent copper and about 60 to 68 percent tungsten. 

2. An electrode contact in accordance with claim 1 wherein the contact member consists essentially of from about 32 to 40 percent copper and about 60 to 68 percent tungsten. 